Audience participation of some kind has been at the heart of much theatre for young people, just as it has been for other theatrical forms that claim an educational or ‘interventionist’ role. Arguably, all theatre is participatory to a degree. Even the audience sitting in formal rows in a traditional auditorium are not passive: their engagement in the drama is an active process of de-coding, responding, and constructing meaning from the variety of stimuli presented. The focus here, however, is with theatrical activity that transgresses the traditional boundary-lines between stage and auditorium and aims to generate an engagement from the audience that is ‘overt and direct, and will often be physical, active and sometimes verbal in form’ (Jackson 2007, p. 136). While audience participation has a rich history throughout the twentieth century (from 1930s agit-prop to Brecht’s lehrstücke to children’s theatre), it is the search for theatrical ways of communicating information, and for generating active learning, that has produced some of the most innovative and challenging forms.